Antilymphocyte antibodies have been found in patients with systemic lupus as well as other connective tissue diseases. We have described a surprisingly high incidence of these antibodies in asymptomatic relatives of SLE patients. These studies suggest that anti-lymphocyte antibodies may be a useful marker of an environmental agent important in the pathogenesis of these diseases. During the next year, I plan to 1) examine in more detail incidence and distribution of anti-lymphocyte antibodies in patients with connective tissue diseases and their families 2) study the specificity of these antibodies 3) examine the role anti-lymphocyte antibodies play in altering or controlling lymphocyte function. BIBLIOGRAPHIC REFERENCES: Mendius, J. R., DeHoratius, R. J., Messner, R. P., and Williams, R. C., Jr.: Family distribution of lymphocytotoxins in Hodgkin's disease. Ann. Int. Med. 84:151-156, 1976. Talal, N., Pillarisetty, R., DeHoratius, R. J., and Messner, R. P.: Immunologic regulation of spontaneous antibodies to DNA and RNA: I Significance of IgM and IgG antibodies in SLE patients and asymptomatic relatives. Clin. Exp. Immunol. 25:377-382, 1976.